Olefinic hydrocarbon stabilized by sodium borohydride particles



United States Patcnt 3,527,821 OLEFINIC HYDROCARBON STABILIZED BY SODIUMBOROHYDRIDE PARTICLES Charles W. Montgomery, Oakmont, and Charles M.Selwitz, Pitcairn, Pa., assignors to Gulf Research & DevelopmentCompany, Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed.Iau. 16, 1968, Ser. No. 698,111 Int. Cl. C07c 7/18; C09k 1/64; C10g9/16 US. Cl. 260-6665 10 Claims ABSTRACT OF THE DISCLOSURE Discreteparticles of sodium borohydride are suspended in olefinic hydrocarbonsfor destruction of olefinic hydroperoxide impurities.

This invention relates to the stabilization of olefinic hydrocarbons.More particularly, this invention relates to the stabilization of alphaolefinic hydrocarbons against the adverse eflfects of hydroperoxideimpurities.

The polymerization of olefin monomers, such as ethylene, in the presenceof an organometallic catalyst, such as triethyl aluminum, to producenormal alpha olefins having from four to about 40 carbon atoms is wellknown. The normal alpha olefins produced, particularly the C C and Calpha olefins, are converted to alkyl chlorides and then used toalkylate benzene as a step in the production of detergents.

The alpha olefins are produced in an oxygen-free atmosphere and arerecovered from the production process in a non-oxygenated condition.However, they are commonly stored outdoors in drums. Cyclic cooling andheating of the drums between daytime and night-time temperatures causesingress and egress of air which reaches the olefins and causeshydroperoxide formation therein. The formation of hydroperoxides in thealpha olefins is autocatalytic so that the rate of hydroperoxideformation increases with the passage of time.

It is very difiicult to remove these hydroperoxide contaminants. Thehydroperoxides formed in the alpha olefins cannot be advantageouslyremoved by distillation because under the elevated temperatureconditions of distillation these peroxides are likely to catalyzepolymerization of the alpha olefin medium in which they are present.

It is known that metal hydrides can be employed in the presence ofsolvents, such as organic polar solvents or water to reducehydroperoxide or peroxide compounds that contain a hydroperoxide radicalor peroxide radical which is attached to a carbon atom to which anotheroxygen atom is attached, i.e.,

Thus, materials such as acetyl peroxide, benzoyl peroxide, peraceticacid, and the like have been reduced by the action of a metal hydride insolution, e.g. an aqueous solution of an alkali metal borohydride. Eachof these compounds contains an oxygen atom connected to the carbon atomto which the hydroperoxide or peroxide group is attached as seen fromthe following structural formulas:

3,527,821 Patented Sept. 8, 1970 Ascaridole Dehydroergosteryl acetateperoxide C 3 CH It has now been found that hydroperoxides which containa hydroperoxide radical attached to a carbon atom to which no oxygenatom is attached, such as those which are formed by the action of air onolefinic hydrocarbons, can be reduced and olefinic hydrocarbons whichare stabilized can be provided. According to the present invention amethod is provided for the stabilization of olefinic hydrocarbons byincorporating an effective amount of finely divided sodium borohydridetherein.

Surprisingly, it has been discovered that if the sodium borohydride issuspended in the olefinic hydrocarbon in the form of discrete particlesrather than in a polar solvent or water, the olefinic hydroperoxideimpurities can be effectively reduced. It was unexpected to find thatsodium borohydride could be employed as the sole reducing agent withouta solvent to reduce the hydroperoxides, since sodium borohydride,itself, is not even soluble in the olefinic hydrocarbon medium. Theemployment of the sodium borohydride in the form of particulate solidsat least partially suspended in the olefinic hydrocarbon, is not onlyellective, but has the great advantage of avoiding the use of a solventmedium, which would only serve to contaminate the olefinic hydrocarbons.The presence of solvent media such as an organic polar solvent woulddestroy the usefulness of the olefinic hydrocarbon as a reactant in thepreparation of detergents by the alkylation of benzene.

The reason that the finely divided sodium borohydride is able to reducethe olefinic hydroperoxides in the absence of a solvent for theborohydride, such as an organic polar solvent or water is not known, sothat no attempt to explain the mechanism can be made. However, aspreviously noted, the fact that the sodium borohydride is not soluble inthe olefinic hydrocarbons and can still re- 3 duce the hydroperoxidestherein is even more surprising, since the sodium borohydride has beenemployed in solution in the past. The chemistry of the reaction whichtakes place can be illustrated by the following equation:

wherein R represents an olefinic hydrocarbon moiety, particularly analpha olefinic hydrocarbon moiety, such as that derived from the alphaolefins described above.

While the finely divided sodium borohydride will effectively destroy thehydroperoxides that are present in the olefinic hydrocarbons, it willnot react with the olefins themselves in the process of the presentinvention. Thus, even at temperatures as high as 20 C., no reactiontakes place between the olefins and the sodium borohydride suspendedtherein.

As previously mentioned, the sodium borohydride is employed in the formof discrete particles. This material is now commercially available, butmay be produced, if desired, by any suitable method. For example, sodiumborohydride may be synthesized by the following reaction employingtemperatures in the range of 225 and 275 C.:

The particle size of the sodium borohydride that is employed in theprocess of the present invention may be varied over a wide range.However, suitable particle sizes include those in the range of between2.5 and about 325 mesh, for example.

The concentration of the sodium borohydride may likewise be varied overa wide range, and any effective amount may be employed. For example,suitable amounts of the borohydride include between about 0.01 and aboutpercent by weight of the olefinic hydrocarbon, preferably between about.1 and about 5 percent by weight. By effective amount of sodiumborohydride, it is intended to include those amounts of the borohydridewhich will reduce substantially all of the hydroperoxides present in theolefinic mixture. The effective amount can be easily determinedexperimentally.

The sodium borohydride will effectively reduce the hydroperoxidespresent in the olefins at a broad range of temperatures. Thus, thereducing action of this material is effective at temperatures ranging,for example, from below room temperature up to about 200 C. Temperaturesin the range of between about and about 200 0, preferably in the rangeof between 60 and 130 C., are quite suitable for the purposes of thepresent invention. The process of the present invention is thereforequite suitable for the stabilization of olefinic hydrocarbons which arestored in closed storage drums in the summer sun. In fact, the rate ofhydroperoxide reduction actually increases with increases intemperature, so that it may be desired to enhance the effectiveness ofthe borohydride stabilizer by employing heated storage containers, tankcars, and the like.

Any olefinic hydrocarbon material may be stabilized by the process ofthe present invention. Thus, for example, the present method may beemployed for the stabilization of olefinic hydrocarbons containingbetween about four and carbon atoms per molecule and mixtures thereof.Examples of suitable olefinic hydrocarbons include 2- butenes, 2pentenes, 3-hexene, Z-heptenes, '12-tetracosene, 4-methyl-2-pentene,cyclohexene, styrene, 1,5-hexadiene; 6-methyl-2-heptenes,3-methylcyclopentene, 2,4,7-trimethyl-1-nonene and the like. However, itis preferred to treat alpha olefins. Thus, for example, the presentmethod may be employed for the stabilization of alpha olefins containingbetween about four and about 40 carbon atoms per molecule and mixturesthereof. Examples of suitable :alpha olefins include, l-butene,l-pentene, l-hexene, 1- hep'tene, l-octene, Z-methyl-l-pentene,4-rnethyl-l-pentene, 4-methyl-1-hexene, 4-ethyl-1-hexene,6-methyl-lheptene, S-methyl-l-heptene, l-nonene, l-decene, l-tridocene,l-nonadecene, l-eicosene, l-heptacosene and the like. It is especiallypreferred to treat alpha olefins containing between about 12 and about16 carbon atoms per molecule.

The contact time between the finely divided sodium borohydride and theolefinic hydrocarbon may be, for example, in the range of between about0.1 and about 10,000 hours or longer, preferably in the range of betweenabout 1 and about 2400 hours. Any suitable reaction pressure may beemployed. However, ordinary at mospheric pressures are quite suitablefor present purposes.

The olefinic hydrocarbons may be admixed with the sodium borohydride inany suitable manner. Thus, the finely divided borohydride can be addedin predetermined amounts to an agitated vessel, such as a stirred kettleor drum containing the olefinic mixture with continued agitation until asuspension of the borohydride is formed. Preferably, the sodiumborohydride is admixed with the olefinic hydrocarbon before anyhydroperoxide compounds have formed, so that the hydroperoxides can bedestroyed as they are formed. Thus, the finely divided borohydride ispreferably added to the olefinic material before it is placed in storagevessels, and the like. This mode of operation minimizes theautocatalytic formation of the hydroperoxides to the greatest extent.However, the borohydride may be added to the olefinic material after thehydroperoxides have formed to destroy hydroperoxides after theirformation. If desired, an inert gas atmosphere may be employed duringthe admixture of the borohydride with the olefinic material in order toexclude oxygen and reduce the formation of hydroperoxides during thisperiod. Thus, nitrogen, carbon dioxide or other inert gases may beemployed under a slight pressure for this purpose.

A more complete understanding of the invention can be obtained byreferring to the following examples which are for illustrative purposesonly.

EXAMPLES 1-4 Auto-oxidized octene-l having a peroxide number of 248 andcontaining about 3 percent octenyl hydroperoxide in the amount of 188grams, is admixed with 3.8 grams of sodium borohydride. The mixture isstirred continuously under a nitrogen atmosphere.

After a period of two hours, a sample of the mixture is taken while atroom temperature. The temperature of the mixture is raised to C. andafter two hours another sample is taken. The temperature is furtherraised to 120 and after two hours a sample is taken. The resultsobtained are set forth below in Table 1.

TABLE 1 Sodium boro Time Tempera- Peroxide Example No. hydride (hours)ture C.) No.

1 N o 0 27 248 2 Yes 0-2 27 3 Yes 2-4 60 25 4 Yes 4-6 0. 2

One hundred grams of hexene-l having a peroxide number of 345 arerefluxed at a temperature of 63 C. with 5 grams of sodium borohydride.The heating is continued for a period of four hours. The peroxide numberis reduced to 35.

EXAMPLE 6 Three hundred grams of a mixture of C to C alpha olefinshaving a peroxide number of 300 are admixed with 6 grams of finelydivided sodium borohydride for a period of about 3 hours. Thetemperature of mixing is about 120 C. This treatment reduces theperoxide number of the mixture to below 0.1.

EXAMPLE 7 A quantity of the C to C stabilized alpha olefinic mixturethat is produced according to Example 6, is reacted with hydrogenchloride and is thereby converted to the corresponding alkyl chlorides.

The alkyl chlorides are then reacted with benzene under alkylationconditions and with a suitable alkylation catalyst to form linear alkylbenzene. A high quality alkylated product is produced and issuccessfully employed in the production of detergents.

EXAMPLE 8 A twenty gallon storage tank is filled with a C to C alphaolefinic hydrocarbon mixture that is produced by the polymerization ofethylene employing a triethyl aluminum catalyst. The storage tank ismaintained at a temperature of 30 C. for a period of seventy (70) days.At the end of this period of time, the contents of the vessel areanalyzed and it is found that some peroxide formation and polymerizationof the alpha olefinic mixture has occurred, presumably due to theautocatalytic formation of hydroperoxide impurities therein.

EXAMPLE 9 The procedure of Example 8, is repeated, except that 4 percentby weight of finely divided sodium borohydride is added to the olefinicmixture, with stirring, prior to placing the olefins into the tank.

After seventy (70) days of storage at 30 C., the contents of the tankare inspected and analysis indicates that no peroxide formation norpolymerization of the alpha olefins has taken place.

Thus, it is seen that the incorporation of the finely divided sodiumborohydride into olefinic hydrocarbons according to the process of thepresent invention results in a stabilized olefinic composition that maybe stored without the autocatalytic formation of peroxides due toreaction of the olefins with air. Furthermore, the suspension of theborohydride in the olefins in the form of discrete particles and in theabsence of a contaminating solvent permits the recovery of a highquality olefinic material that is suitable for industrial applications,e.g., detergent production.

Obviously, many modifications and variations of the invention ashereinabove set forth can be made without departing from the spirit andscope thereof; and therefore only such limitations should be imposed asare indicated in the appended claims.

We claim: 1. A method for the stabilization of an olefinic hydrocarbonby the destruction of olefinic hydroperoxide contaminants, whichcomprises admixing said olefinic hydrocarbon with an effective amount ofdiscrete particles of sodium borohydride in the substantial absence of asolvent for said sodium borohydride.

2. The method of claim 1 wherein the olefinic hydrocarbon is an alphaolefin.

3. The method of claim 2 wherein the alpha olefin contains between 4 and40 carbon atoms.

4. The method of claim 1 wherein the resulting admixture is employed attemperatures in the range of between about room temperature and 200 C.

5. The method of claim 1 wherein the admixture is conducted in thepresence of an inert atmosphere.

6. The method of claim 1 wherein the hydroperoxides contain ahydroperoxide radical attached to an olefinic hydrocarbon moiety.

7. The method of claim 6 wherein the olefinic hydrocarbon moiety is analpha olefinic moiety.

8. A stabilized composition of matter consisting essentially of anolefinic hydrocarbon containing discrete particles of sodium borohydridesuspended therein.

9. A composition of matter as defined in claim 8 wherein the olefinichydrocarbon is an alpha olefin.

10. A composition of matter as defined in claim 9 wherein the alphaolefin contains between 12 and 16 carbon atoms per molecule.

References Cited UNITED STATES PATENTS 2,867,651 1/1959 Wise 252--188 X2,967,897 1/1961 Sharp et al. 260-681 3,373,174 3/1968 Hammerberg et a1.

260l X 3,420,906 1/1969 Singleterry 260666.5

OTHER REFERENCES Encyclopedia (III), Borohydrides, by Hinckley, pp.v

210-217, vol. 11 (1967).

Matic and Sutton: Reduction of Tetralyl Peroxide with SodiumBorohydride, Chem. & Ind., London, 1953, p. 666.

DELBERT E. GANTZ, Primary Examiner G. E. SCHMITKONS, Assistant ExaminerUS. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,527,821 September 8, 1970 Charles W. Montgomery et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, line 31, in the terminal group at the bottom of I the chain"CH" should read CH3 Column 3, line 14,

"20 C." should read 200 C.

Signed and sealed this 5th day of January 1971.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

